linux-kernel - [PATCH v2 2/4] PCI/MSI: Add startup/shutdown for per device domains

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Message-ID: <20250813232835.43458-3-inochiama@gmail.com>
Date: Thu, 14 Aug 2025 07:28:32 +0800
From: Inochi Amaoto <inochiama@...il.com>
To: Thomas Gleixner <tglx@...utronix.de>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Marc Zyngier <maz@...nel.org>,
	Lorenzo Pieralisi <lpieralisi@...nel.org>,
	Shradha Gupta <shradhagupta@...ux.microsoft.com>,
	Haiyang Zhang <haiyangz@...rosoft.com>,
	Inochi Amaoto <inochiama@...il.com>,
	Jonathan Cameron <Jonathan.Cameron@...ei.com>,
	Juergen Gross <jgross@...e.com>,
	Nicolin Chen <nicolinc@...dia.com>,
	Jason Gunthorpe <jgg@...pe.ca>,
	Chen Wang <unicorn_wang@...look.com>
Cc: linux-kernel@...r.kernel.org,
	linux-pci@...r.kernel.org,
	Yixun Lan <dlan@...too.org>,
	Longbin Li <looong.bin@...il.com>
Subject: [PATCH v2 2/4] PCI/MSI: Add startup/shutdown for per device domains

As the RISC-V PLIC can not apply affinity setting without calling
irq_enable(), it will make the interrupt unavailble when using as
an underlying IRQ chip for MSI controller.

Implement .irq_startup() and .irq_shutdown() for the PCI MSI and
MSI-X templates. For chips that specify MSI_FLAG_PCI_MSI_STARTUP_PARENT,
these startup and shutdown the parent as well, which allows the
irq on the parent chip to be enabled if the irq is not enabled
when allocating. This is necessary for the MSI controllers which
use PLIC as underlying IRQ chip.

Suggested-by: Thomas Gleixner <tglx@...utronix.de>
Signed-off-by: Inochi Amaoto <inochiama@...il.com>
---
 drivers/pci/msi/irqdomain.c | 52 +++++++++++++++++++++++++++++++++++++
 include/linux/msi.h         |  2 ++
 2 files changed, 54 insertions(+)

diff --git a/drivers/pci/msi/irqdomain.c b/drivers/pci/msi/irqdomain.c
index 0938ef7ebabf..e0a800f918e8 100644
--- a/drivers/pci/msi/irqdomain.c
+++ b/drivers/pci/msi/irqdomain.c
@@ -148,6 +148,23 @@ static void pci_device_domain_set_desc(msi_alloc_info_t *arg, struct msi_desc *d
 	arg->hwirq = desc->msi_index;
 }
 
+static void cond_shutdown_parent(struct irq_data *data)
+{
+	struct msi_domain_info *info = data->domain->host_data;
+
+	if (unlikely(info->flags & MSI_FLAG_PCI_MSI_STARTUP_PARENT))
+		irq_chip_shutdown_parent(data);
+}
+
+static unsigned int cond_startup_parent(struct irq_data *data)
+{
+	struct msi_domain_info *info = data->domain->host_data;
+
+	if (unlikely(info->flags & MSI_FLAG_PCI_MSI_STARTUP_PARENT))
+		return irq_chip_startup_parent(data);
+	return 0;
+}
+
 static __always_inline void cond_mask_parent(struct irq_data *data)
 {
 	struct msi_domain_info *info = data->domain->host_data;
@@ -164,6 +181,23 @@ static __always_inline void cond_unmask_parent(struct irq_data *data)
 		irq_chip_unmask_parent(data);
 }
 
+static void pci_irq_shutdown_msi(struct irq_data *data)
+{
+	struct msi_desc *desc = irq_data_get_msi_desc(data);
+
+	pci_msi_mask(desc, BIT(data->irq - desc->irq));
+	cond_shutdown_parent(data);
+}
+
+static unsigned int pci_irq_startup_msi(struct irq_data *data)
+{
+	struct msi_desc *desc = irq_data_get_msi_desc(data);
+	unsigned int ret = cond_startup_parent(data);
+
+	pci_msi_unmask(desc, BIT(data->irq - desc->irq));
+	return ret;
+}
+
 static void pci_irq_mask_msi(struct irq_data *data)
 {
 	struct msi_desc *desc = irq_data_get_msi_desc(data);
@@ -194,6 +228,8 @@ static void pci_irq_unmask_msi(struct irq_data *data)
 static const struct msi_domain_template pci_msi_template = {
 	.chip = {
 		.name			= "PCI-MSI",
+		.irq_startup		= pci_irq_startup_msi,
+		.irq_shutdown		= pci_irq_shutdown_msi,
 		.irq_mask		= pci_irq_mask_msi,
 		.irq_unmask		= pci_irq_unmask_msi,
 		.irq_write_msi_msg	= pci_msi_domain_write_msg,
@@ -210,6 +246,20 @@ static const struct msi_domain_template pci_msi_template = {
 	},
 };
 
+static void pci_irq_shutdown_msix(struct irq_data *data)
+{
+	pci_msix_mask(irq_data_get_msi_desc(data));
+	cond_shutdown_parent(data);
+}
+
+static unsigned int pci_irq_startup_msix(struct irq_data *data)
+{
+	unsigned int ret = cond_startup_parent(data);
+
+	pci_msix_unmask(irq_data_get_msi_desc(data));
+	return ret;
+}
+
 static void pci_irq_mask_msix(struct irq_data *data)
 {
 	pci_msix_mask(irq_data_get_msi_desc(data));
@@ -234,6 +284,8 @@ EXPORT_SYMBOL_GPL(pci_msix_prepare_desc);
 static const struct msi_domain_template pci_msix_template = {
 	.chip = {
 		.name			= "PCI-MSIX",
+		.irq_startup		= pci_irq_startup_msix,
+		.irq_shutdown		= pci_irq_shutdown_msix,
 		.irq_mask		= pci_irq_mask_msix,
 		.irq_unmask		= pci_irq_unmask_msix,
 		.irq_write_msi_msg	= pci_msi_domain_write_msg,
diff --git a/include/linux/msi.h b/include/linux/msi.h
index e5e86a8529fb..3111ba95fbde 100644
--- a/include/linux/msi.h
+++ b/include/linux/msi.h
@@ -568,6 +568,8 @@ enum {
 	MSI_FLAG_PARENT_PM_DEV		= (1 << 8),
 	/* Support for parent mask/unmask */
 	MSI_FLAG_PCI_MSI_MASK_PARENT	= (1 << 9),
+	/* Support for parent startup/shutdown */
+	MSI_FLAG_PCI_MSI_STARTUP_PARENT	= (1 << 10),
 
 	/* Mask for the generic functionality */
 	MSI_GENERIC_FLAGS_MASK		= GENMASK(15, 0),
-- 
2.50.1